This application claims the priority of Japanese Patent Application Nos. 6-232021 and 6-232020 filed on Sep. 1, 1994.
1. Field of the Invention
The present invention relates to a structure of the end portion of a side-looking type electronic endoscope which is provided with an irradiation window, an observation window and a forceps insertion hole arranged on the side surface thereof.
2. Description of the Related Art
FIGS. 9 and 10 show the structure of the end portion of a conventional side-looking type electronic endoscope. An observation window 2 and an irradiation window 3 are arranged on the side surface of the end portion 1 of the endoscope. A CCD (Charge Coupled Device) 5 is attached to the observation window 2 via an optical system member 4, and a signal cable 7 is connected to the printed circuit board 6 of the CCD 5. The signal cable 7 is led to, for example, an external processor apparatus. A light guide 8 is attached to the irradiation window 3. The light guide 8 is finally connected to a light source device. A raising table 10 connected to a wire 9 and supported by a shaft 11 is disposed in parallel with the observation window 2, as shown in FIG. 10, and a forceps insertion hole is provided behind the raising table 10. By raising the raising table 10 by pulling the wire 9, it is possible to lead a manipulating tool 12 from the side surface (through the forceps insertion hole) up to a predetermined position or in a predetermined direction, as shown in FIG. 9.
According to this structure of the end portion 1, the light supplied through the light guide 8 is projected into the body as the object of inspection through the irradiation window 3, and the image of the internal body is caught by the CCD 5 via the observation window 2 and the optical system member 4. The picture signals obtained by the CCD 5 are input to the external processor device or the like through the signal cable 7 and processed by the external processor device. As a result, the image of the internal body is displayed on a monitor. At the same time, it is possible to lead the manipulating tool 12 from the side surface of the end portion 1 so as to execute various treatments.
In a conventional side-looking type electronic endoscope, since the observation window 2 is disposed closer to the end than the irradiation window 3, there is a problem that a shadow is cast on the surface (an inclined surface or the like) of a protruding or recessed portion within the body which faces in the direction of insertion of the endoscope, or that the surface is shaded. For example, in the case of the mammilation of the duodenum, which is a representative part treated by an endoscope, the endoscope 14 is inserted into the duodenum 16 through the stomach 15, so as to conduct a predetermined treatment on the mammilation 19 having an opening portion which opens into the bile duct 17 and the ductus pancreaticus 18, as shown in FIG. 11. However, since the mammilation 19 is a protruding portion, as shown in FIG. 11, when light is projected from the irradiation window 3 disposed at the rear portion, the opening portion of the mammilation 19 is shaded, and it is difficult to treat the opening portion with the manipulating tool 12.
The same problem is produced in the observation of a diverticulum. In many cases, it is more convenient to dispose the irradiation window 3 closer to the end than the observation window 2. In order to dispose the irradiation window 3 closer to the end than the observation window 2, it is also necessary to dispose the light guide 8 in the vicinity of the end, which inconveniently increases the diameter of the endoscope. That is, as is clear from FIG. 10, since the optical system member 4, the CCD 5, the printed circuit board 6, the signal cable, 7, etc. are connected to the observation window 2, there is no place to dispose the light guide 8 in the state shown in FIG. 10, so that it is necessary to increase the diameter of the endoscope. However, an endoscope is required to have as small a diameter as possible in order to alleviate the pain of a patient.
In addition, in a conventional endoscope, when the printed circuit board or the like as well as the CCD is replaced, it is sometimes necessary to remove the light guide depending upon the structure of the end portion. However, since the endoscope adopts an airtight structure, the light guide is tightly adhered to the supporting portion with an adhesive or the like. It takes much time to remove the light guide, and the light guide itself is sometimes broken.